This invention pertains to devices which are fabricated using photoactivated thermal transfer elements as described in U.S. Pat. No. 6,946,178 and U.S. Pat. No. 7,141,348 by Sheats et al., which are hereby incorporated by reference. These patents disclose a method of transferring, or printing, thin film devices from a donor substrate (also here called a donor plate), on which the polymeric photoactivated thermal transfer material has been applied, onto a target substrate. In this process, irradiation with actinic light is used to selectively activate the polymer under a device which the user wishes to transfer, while leaving other devices on the same substrate unactivated. Heating the polymer (referred to herein as a Digital Release Adhesive, or DRA) causes it to vaporize and transfer the device to a target substrate in close proximity while leaving the unactivated devices on the donor substrate. By this method, such objects as very small integrated circuit chips, with lateral dimensions of less than 100 μm, for example, which are difficult or impossible to handle effectively by other means such as the pick and place machines which are well known in the art, can be placed onto product substrates at very high speed. The described process is advantageously used for small and thin silicon chips, but may also be used with any object which is thin enough to be readily adhered to a thin polymer film; for example light emitting diodes, thin film sensors, MEMS devices, thin film capacitors or resistors, any semiconductor device or component, and other electronic or optical components, some of which are described in the referenced patents by Sheats et al.
FIG. 1 illustrates a prior art transferring process according to some embodiments. Multiple chips 130 can be adhered to a donor plate 110 through a layer 120 of a polymeric photoactivated thermal transfer material. By radiating, e.g., using a visible light or a laser beam 140, together with an optional heating process, the portion 122 of the polymeric photoactivated thermal transfer material can be evaporated, releasing chip 132 onto a substrate 150.
There is a need for printing multiple components on a chip module with high throughput using polymeric photoactivated thermal transfer material.